Stalactites, stalagmites, columns, and lacelike rock on multiple levels fill the fascinating Jenolan Caves, a labyrinth of vast limestone caverns sculpted by underground rivers. There are as many as 320 caves in the Jenolan area. Two caves (Nettles Cave and Devil's Coachhouse) near the surface can be explored on your own, but a guide is required to reach the most intriguing formations. Standard tours lead through the most popular caves—many say that Orient Cave is the most spectacular, while the more rigorous adventure tours last up to seven hours. The one- to two-hour walks depart every 15 to 30 minutes, on weekends less frequently. Prices range from A$35 for a standard tour to A$220 for the full-day Mammoth Cave Adventure Tour where you squeeze through ancient passageways—it includes a bit of rappelling and is not for the claustrophobic. Concerts and murder mystery nights are also held in this spooky environment. Cave House, on the same site, is a nostalgic retreat and has been providing lodging since 1887. To get here, follow the Great Western Highway north out of Mount Victoria, then after Hartley, turn southwest toward Hampton.